This invention relates to polyphosphazene polymers containing repeating ##STR2## units in the polymer chain in which substituted and unsubstituted nitrophenoxy substituents are attached to the phosphorus atom. More particularly, the invention relates to polyphosphazene polymers having substituents derived from nitrophenols attached to the phosphorus atom, and substituent mixtures of nitrophenol substituents and substituted or unsubstituted aliphatic or aromatic alcohols, amino compounds and mercaptan compounds, and to a method of preparing such polymers.
Polyphosphazene polymers containing repeating ##STR3## units in which various alkoxy, substituted alkoxy, aryloxy and substituted aryloxy groups are attached to the phosphorus atom and their method of preparation are described in the prior art as illustrated in the publication "Phosphorus Nitrogen Compounds", Academic Press, New York, N.Y. 1972 by H. R. Allcock and "Poly(Organophosphazenes)", Chemtech, Sept. 19, 1975 by H. R. Allcock and in such U.S. Pat. Nos. as 3,515,688; 3,702,833; and 3,856,712.
U.S. patent application Ser. No., 796,073, filed May 12, 1977 now abandoned (commonly assigned) discloses a sodium process using p-nitrophenol. Due to the reaction media (sodium process) and the nature of the product (a yellow material where this application yields a white or clear product), it is believed this disclosure does not yield a polyphosphazene polymer with the nitrophenoxy substituent. It is believed the product of this prior disclosure is some reduced form or condensed form of the nitro group. Also, the sodium process would not permit the high levels of nitrophenoxy substituent in the polyphosphazene that are obtained by this invention. The prior disclosure would yield, due to the sodium process, phenoxy substituents of less than 5 percent (3 percent actually yielded) whereas this invention yields at least 10 mole percent and preferably over 20 mole percent of the nitrophenoxy substituent on the polyphosphazene.